Illumination of body cavities for diagnosis and/or therapy is typically provided by overhead lighting or by headlamps. These forms of illumination can be challenging to use under certain situations. For example, overhead lighting must constantly be adjusted as the physician's position changes relative to the patient, as well as to illuminate different parts of the surgical field. Also, overhead lighting devices may require sterile handles to be attached to the lights in order for the physician to make adjustments without breaching the sterile field. Even then, the light provided by the overhead lamp may not illuminate the work space adequately. Head lamps can be heavy and uncomfortable to use, may require an assistant to help a physician put the headlamp on, and they often generate considerable amounts of heat during use which further limits comfort and can cause burns if an operator accidently mishandles the head lamp. Head lamps also require the physician to constantly adjust head position in order to illuminate the work space, and this can be uncomfortable to the physician.
In an attempt to address some of these issues, surgical instruments such as retractors have been coupled with light pipes such as fiber optics to conduct light from a light source such as a halogen light or a LED light source in order to illuminate a surgical field. For example, some conventional illuminated soft tissue retractors utilize a fiber optic light bundle attached to a retractor handle. The fiber optic bundle provides a very focused light and generates a significant amount of heat. The fiber optics tube is also typically in the line of sight of the user, thereby obstructing a surgeon's view in use. Also, the fiber optic bundle only provides a narrow spot of light and must be constantly adjusted to illuminate the surgical field and minimize glare or shadows. Additionally, the fiber optic bundle requires precision manufacturing and polishing, and the fibers are fragile and can be easily scratched, occluded by blood or other debris, or otherwise damaged in use. Thus fiber optic bundles can also be challenging to use in illuminated surgical systems.
Other materials may be used as waveguides that overcome some of the challenges associated with fiber optic bundles. Exemplary materials such as acrylic or polycarbonate have also been used as waveguides, but these materials have unstable light transmission characteristics under extended use, and the transmission characteristics may change after sterilization using convention techniques. For example, many polymers cross-link and yellow or become brittle after terminal sterilization with radiation. Heat from autoclaving or ethylene oxide sterilization can deform the waveguide. Additionally, precision optical polymers have limited mechanical properties which can limit their use in medical and surgical procedures. For example, some polymers are brittle and can easily shatter during use, or are difficult to process during manufacturing (e.g. hard to injection mold).
In addition to some of the challenges with illumination of a surgical field, surgical instruments such as retractor blades do not always accommodate the anatomy being treated, and the retractor blade and illumination device coupled to the retractor takes up precious space in the surgical field
Therefore, it would be desirable to provide improved illuminated medical devices that provide better illumination of a work space and that reduce or eliminate some of the weight and heat constraints of traditional headlamps and overhead lighting. Such devices conform to the anatomy being treated, are easy to place, and have low profile so they do not take up significant amounts of space, thereby allowing more room for a surgeon's hand or other surgical instruments, and avoiding obstruction of the work space. Additionally, it would be desirable to provide such devices that provide superior lighting to allow visualization of the surgical field, including adjacent tissues such as nerves or blood vessels. Such devices preferably are easy to manufacture, may be single-use or re-sterilizable, and have desired mechanical properties in service. Such instruments also have low profiles so the instrument can fit through small incisions or be positioned in small surgical fields which reduce scarring, improve healing time, and reduce hospital stay. At least some of these objectives will be addressed by the embodiments disclosed herein.